Substituted piperidine hydroxamides, their preparation, and their use as light stabilizers

Abstract

The invention provides novel derivatives of 2,2-dimethyl-6,6-dialkyl-4-hydroxy-4'-carbamoyl-piperidines which carry a substituent at the amide nitrogen atom, and optionally a further substituent at the ring nitrogen atom, and a process for preparing these compounds. The products, optionally in the form of salts, are used for stabilizing thermoplastics against the damaging influence of light.

What is claimed is: 
     
       1. A process for the preparation of piperidine hydroxyamides of the formula ##STR4## in which R 1  and R 2  are methyl; R 3  is tertiary alkyl of 4-8 carbons; and   R 4  is hydrogen or alkyl of 1-4 carbons, which comprises reacting 2,2,6,6-tetramethyl-4-hydroxy-4-cyanopiperidine in an organic solvent with a tertiary alcohol of 4 to 8 carbons or an olefin of the same number of carbons, with addition of sulfuric acid as catalyst, in which process when an olefin is used at least an equimolar amount of water is added after the reaction is complete.